Snowmobiles are popular vehicles for use in snowy conditions and can be used for utilitarian or recreational purposes. Although primarily a recreational vehicle, snowmobiles are often relied upon for transportation in remote areas where road vehicles are disabled because of poor road conditions. When used as a primary mode of transportation, it is desirable that the snowmobile be capable of hauling a load, as for example, on a towed trailer. Additionally, it may be necessary to tow a disabled snowmobile from a remote area inaccessible to general road vehicles.
A typical snowmobile may be equipped with a hitch receiver mounted at the rear of the vehicle for coupling a towed object such as a trailer, other cargo transport, or a disabled snowmobile. Typical snowmobile hitch systems have been cumbersome to install and operate, requiring complicated mounting. Additionally, typical hitch receivers extend out from the body of the snowmobile thereby detracting from aesthetics and aerodynamic properties of the snowmobile.
Because snowmobiles are often operated on uneven terrain, excessive torsional forces can be applied to the portion of the snowmobile carrying the hitch receiver, damaging the snowmobile and placing the operator in danger.
Trailer hitch assemblies for coupling a towed object, such as a trailer or vehicle, to a towing vehicle are well known. Typical trailer hitch assemblies include a two part arrangement with a ball assembly mounted to the towing vehicle and socket assembly, for receiving the ball. Such a coupling is known as a ball and socket joint.
The traditional ball and socket trailer hitch systems have two major limitations. First, the ball and socket coupling produces excessive torsional and angular stresses on the bumper. During towing, over uneven terrain or when making turns or corners there is differential horizontal and vertical displacement between the towed object and the towing vehicle. Such stresses can be so severe as to damage the bumper, the trailer hitch, or both and place the driver in danger. Second, the ball and socket must be specifically mated, that is, the ball assembly is only capable of coupling a towed object equipped with a correctly sized socket assembly. Thus, when a trailer that is not equipped with a socket assembly is encountered either the trailer or vehicle hitch system must be altered.
A further shortcoming of prior art trailer hitch assemblies involves the often cumbersome and complicated manner in which the towed object is uncoupled from the towing vehicle. For example, in the traditional ball and socket hitch system, the tongue member of the towed object must be lifted upward to uncouple the socket. This is particularly cumbersome when a heavy load is towed. Often, the trailer must be provided with a jack to enable the operator to lift the socket off the ball.
With respect to hitch assemblies for snowmobiles in particular, it has often been necessary to change the hitch receiver to mate with the particular hitch mount provided on any particular towed object. This often involves disassembly of the rear bumper of the snowmobile and the drilling of multiple holes to accommodate various hitch receiver types. Such a system is undesirable especially if the snowmobile is used to tow a variety of trailers or other towable objects. Furthermore, the aesthetics of the snowmobile are compromised by the plurality of holes drilled in the chassis.
A number of developments have been made to improve the traditional ball and socket trailer hitch assembly. For example U.S. Pat. No. 4,548,423 discloses a universal trailer hitch assembly having a mounting block that receives a shaft member extending from a universal joint. The shaft is configured to be mounted to a towing vehicle between two blocks. A stationary block mounts to the towing vehicle and a removable block sandwiches the keyed shaft of the universal joint between itself and the stationary block to provide the coupling between the towed object and the towing vehicle. The rotation of the shaft member in the mounting block reduces torsional forces. To uncouple the towed object from the towing vehicle, tools are required to disconnect the shaft from the blocks.
U.S. Pat. No. 4,588,199 discloses a swivel connection for trailers adapted to be interposed between a motorcycle or other small vehicle and a trailer. The swivel connector is formed of an elongated hollow bar welded at one end to a socket portion of a trailer hitch assembly. An open ended box is welded within the interior of the hollow bar at an end opposite the socket. A spindle is welded within the open-ended box. The spindle of the socket portion of the hitch assembly is journalled in an open-ended sleeve provided on the tongue member of a trailer for horizontal rotation thereabout. Thus, to benefit from the degree of rotation afforded by the swivel connector, each trailer or towed object must be fitted with the swivel connector.
U.S. Pat. No. 3,797,846 discloses a tow bar with a pivotable tongue for coupling a snowmobile to be towed to a towing snowmobile. Torsional forces are reduced by providing a tongue with a threaded bolt mounted in the internal space of the tongue. The towing vehicle and towed object are coupled together via a threaded bolt that is received within the bolt of the tongue. Torsional forces are essentially taken up by the screwing and unscrewing (depending on the direction of the force) of the threaded bolt.
U.S. Pat. No. 3,552,775 discloses a trailer hitch coupling configured to reduce torsional forces. The coupling is comprised of a pintle formed with annular grooves. Annular rings sized to be received within the annular grooves allow the pintle to rotate against the annular rings. One end of the pintle is provided with metal plates for mounting to a traditional trailer hitch. The other end is received within a terminus of an auto tow bar. There is also provided a number of adaptors to adjust the pintle for use in varying sized and shaped receivers. While allowing for reduction in torsional forces, the coupling requires the use of inconvenient adapters, multiple parts, and is cumbersome to uncouple the towed object from the towing vehicle.
While there have been previous attempts to accommodate differential movement and torsional forces, none satisfy the requirement of simultaneously reducing torsional forces on the towing vehicle while being freely and easily interchangeable for use with a variety of tongue configurations provided on towable objects. Furthermore, none of the prior art assemblies provide for a convenient and efficient manner of uncoupling the towed object from the towing vehicle. There remains a need, therefore, for a trailer hitch system satisfying these requirements.